This invention relates to the measurement and control of tension in a moving elongate flexible element such as a threadline, and more particularly to a precision tensiometer of unusually rugged structure which is insensitive to vibration and able to withstand large mechanical shocks. Although not restricted to such use, this invention is particularly applicable to the measurement of tension in continuous textile yarn while it is being manufactured and wound on packages at the end of a high-speed spinning machine.
Tension transducers have taken many forms in the past. For example, Nieuweboer in U.S. Pat. No. 3,444,731, teaches the use of a guide pin supported in a resilient linkage under constraint and with displacement transducers to measure the effects of yarn tension. Harvey in U.S. Pat. No. 3,376,740, shows a tensiometer designed to reduce vibration effects. He uses twin, back-to-back elastic sensing arms each with a strain gage thereon and with yarn running over only one arm. Output signals from each gage are connected in such a way as to reduce signal noise due to mechanical vibration. Roberts in U.S. Pat. No. 3,512,406 shows a robust tensiometer comprising a long cylindrical guide cantilevered from a support and provided with a strain gage near its supported end. Although these guides each have some important attributes either of ruggedness or of ability to suppress vibration effects, none is sufficiently sensitive, nor do they combine the ability to withstand shocks (such as being struck by a sucker gun during stringup) as well as being able to suppress machine vibration effects.